I was bumming around Reddit the other day when I came across a discussion talking about how laser guns in Warhammer 40,000 have appreciable recoil, enough that a laser sniper rifle was described as having a kick strong enough to leave a bruise on ones' shoulder. Now I know 40k plays fast and loose with the laws of physics even compared to most science-fiction series, but this seemed incredulous even to me. It was my understanding that laser weapons would have no recoil since photons do not have appreciable mass, only momentum, or the amount of force they would apply to the firer would be absolutely miniscule. I've also not heard much about real life lasers ever having significant recoil.
What's more surprising is that nobody in the actual threads seemed to be able to figure out whether laser weapons would have appreciable recoil. In both the discussion and another linked blogpost, people propose all sorts of explanations saying "yes it would have recoil", "no it would not have recoil", or "yes but the recoil would be slight", and it's hard to tell which are accurate to real life physics. The links are posted below if anyone is interested in the actual explanations given.
So my question here is would a laser weapon have significant recoil or not? And by this I mean an actual laser weapon, not a particle gun dressed up as a laser or misidentified as one like Star Wars blasters.